1. Field of the Invention
The present invention generally relates to dispensing equipment and, more particularly, but not by way of limitation, to a control assembly for a beverage dispensing system cooling unit. The control assembly regulates growth of a frozen cooling bank to achieve optimal thermodynamic performance under various conditions.
2. Description of the Related Art
In the beverage dispensing industry, it is highly desirable to serve drinks at a designated cold temperature. To accomplish this, beverage dispensing systems typically include cooling units to lower the temperature of beverage fluids, such as flavored syrup and a diluent of plain or carbonated water, prior to forming and dispensing a desired beverage.
One cooling unit well known in the industry is a refrigeration unit featuring a cooling fluid bath. The cooling fluid bath includes a cooling chamber filled with a cooling fluid, which is typically water, disposed within a beverage dispenser. The cooling unit includes an evaporator coil that extends from the cooling unit into the cooling chamber so that the evaporator coil is submerged within the cooling fluid. While the cooling unit is in operation, cooling fluid freezes in a bank around the evaporator coil. Beverage lines submerged within the unfrozen cooling fluid contain warm beverage fluids. The unfrozen cooling fluid serves as an intermediary for convective heat exchange between the beverage fluids and the frozen bank. Effectively, the frozen bank functions as a heat sink by absorbing heat from warm beverage fluids flowing within respective beverage lines. As beverage fluids are dispensed, the cooling unit is turned on and off to maintain a properly sized frozen bank. Maintaining a frozen bank of proper size and shape is essential to maintaining optimal thermal performance of the cooling unit.
Unfortunately, current designs for beverage dispensing units do not provide for accurate growth control of the frozen bank resulting in improper sizes and shapes. As a result, the thermal performance of the cooling unit suffers. Generally, frozen banks are shaped by positioning a single sensor unit at a desired distance from the evaporator coil within the bath of unfrozen cooling fluid. When the sensor unit detects a desired size of the bank, the sensor unit sends a signal to turn off the cooling unit to stop the growth of the bank. However, external factors can cause undetected deformities in the bank because the size and shape of the bank is monitored at only one location.
For example, two external factors are dispensing valve temperature loading and ambient temperature conditions. Typically, dispensing valve temperature loading is caused by frequent use of a particular, often popular, dispensing valve. When this happens, the associated beverage line raises to a higher temperature than the rest of the beverage lines. As a result, an adjacent region of the bank will melt while absorbing the heat from the higher temperature beverage line. Unfortunately, if the single sensor unit is located in another region, it cannot detect this localized melting. Therefore, continued use of the same dispensing valve will result in the dispensing of beverage fluids at a higher than desired temperature. In contrast, if the single sensor is located at the region of localized melting, the sensor will signal the cooling unit to turn on resulting in overgrowth of the bank at other regions. Overgrowth of the bank can damage beverage dispensers by freezing the beverage fluid lines and, potentially, freezing an entire cooling fluid bath. Additionally, extreme ambient temperature conditions can also cause other undetected deformities in the frozen bank. Extremely hot ambient conditions can cause imbalanced reduction in size of the frozen bank. This condition can result in inadequate thermodynamic performance. Extremely cold ambient temperatures can cause overgrowth of the bank resulting in the same problems as described above.
In as much, the unfavorable formation of misshapen banks greatly disrupts the optimal circuitous path of convective heat transfer created between the warm beverage fluids within the beverage fluid lines and the bank. Accordingly, there is a long felt need for a apparatus and method for a beverage dispensing system cooling unit that regulates growth of a frozen cooling bank for optimal thermodynamic performance.